Researcher(s)
- Abigail Krams, Neuroscience, University of Delaware
Faculty Mentor(s)
- Dayan Knox, Psychological and Brain Sciences, University of Delaware
Abstract
Post traumatic stress disorder (PTSD) is a chronic psychiatric disorder characterized by hypervigilance, distorted beliefs, sleep disturbances, memory and concentration issues, flashbacks, and reckless behavior. About 90% of the general population has experienced one or more traumatic events, but most only experience acute distress immediately following the event and do not develop PTSD. On the other hand, development of PTSD is due to a failure to adapt or recover following exposure to a traumatic event. Females are 2-3 times more likely to develop PTSD following a traumatic event than males; however, the neurobiological mechanism underlying this discrepancy is largely unknown. One possible explanation lies in the endogenous opioid system where abnormalities have been recorded following PTSD symptom development. The endogenous opioid system is a reward circuit implicated in positive reinforcement and stress responses. Perturbation to this reward system can cause differences, or even dysfunction, in endogenous opioid receptors, specifically mu-opioid receptors (MORs). Mu-opioid receptors are implicated in many biological processes and there is evidence that single prolonged stress may have a similar effect to opioid use disorders (OUDs) on the internalization and expression of MORs. This connection lies primarily in the significant comorbidities of PTSD and OUDs, potentially linking them neurobiologically. In this study, female Sprauge Dawley rats were exposed to either single prolonged stress or control conditions, then euthanized. The medial prefrontal cortex, amygdala, and ventral and dorsal hippocampus were then isolated, the cytoplasmic and membrane proteins were extracted and separated, and were finally assayed via Western blot to quantify MOR internalization. No significant differences were observed in these regions. Future research should focus on novel methods to isolate and quantify the expression of MOR in order to identify if there is a correlation between sex discrepancies observed in PTSD.